Presuming you're not still picking your jaw up from the floor at the fact that this slender beauty struts and poses as a plus-size model, (at a whopping UK size 10!) you will, no doubt, be admiring her sophisticated, little black ensemble that she wore to the opening of the Z Spoke by Zac Posen store in New York. From the Fall 2011 Z Spoke collection by the designer himself, Ms. Renn looked ravishing in this classic, backless jersey dress with on-trend, mid-length hemline, leaving us in no doubt as to why this elegant model is a regular on the Zac Posen runways. Attending the event alongside fellow fashionista, Ally Hilfiger, Crystal Renn flaunts just one of the many stunning little black dresses that belong to Posen's latest collection which features classic cuts accented with all sorts of twists and turns, exaggerated hips and cheeky cut-outs. This season we're looking to make like Olivia Wilde, Zooey Deschanel and Laura Haddock and dramatise our LBD wardrobe with some glorious designer evening dresses.  Zac Posen has this look nailed so cast your eye over our favourite Posen pieces for some inspiration.